Tools or work instruments often include moveable members, such a bit for a drill or a moveable surface for a work table. These moveable members are traditionally operated by servomotors, which are, in turn, regulated by servo controllers. A position detector on a tool typically measures the position or velocity of the moveable member, and transmits a signal to the servo controller. The servo controller subsequently controls the servomotor so that the position or velocity of the moveable member matches an input value. The input value is generated within numeric control apparatus, and the servo controller is but one component of the numeric control apparatus.
The development of modern control theory has had a profound effect upon the development and design of servo systems for machine tools. Modern control theory requires that a control system be dynamically modeled, by creating a mathematical model of the system known as a state equation, including a system parameter. In general, this approach is more complex than the design of a controllers which utilize conventional proportional-integral-derivative (“PID”) controllers.
In order to model the controlled system, an identification experiment must be performed, in which reference inputs are supplied to the servo controller. The servo controller controls the servomotor in the machine tool, which in turn operates the moveable member. Measurement data is collected for each reference input, representing the various states of the moveable member, and the measurement data stored in the memory of the numeric controller. Typically, the measurement data is then transferred from the numeric controller to an external computer in which a mathematical tool such as MATLAB® is installed, via a serial interface. The computer models the controlled system based on the reference inputs and corresponding measurement data.
Using the collected measurement data, a virtual controller is designed and simulated using the computer, based on the state equation or model of the controlled system. If the controlled system operates according to specifications using the simulated controller, a physical controller is manufactured for use in the numeric controller. Otherwise, gains in the virtual controller are adjusted until simulation results become adequate.
As such, while measured data is typically gathered in the numeric controller, the modeling and design of the controller are ordinarily performed in an external computer. The drawback to this technique is that the model must be generated externally.
Accordingly, it is desirable to provide for a numeric control apparatus for machine tools to overcome the drawbacks of conventional numeric control apparatus. Additionally, it is desirable to provide a numeric control apparatus for machine tools capable of modeling the controlled system, and designing and simulating a controller, in order to overcome the drawbacks of prior art modeling systems.